Leptin is a 16 KDa protein secreted by adipocytes which plays an important role not only in regulating apetite and energy expenditure, but also in the function of other systems including neuroendocrine, hematopoetic and immune systems. Recent studies have shown association between circulating leptin concentration and bone mineral density. Although some experimental studies revealed an inverse relationship between leptin and bone mass, human studies have reported either no association or a weak positive correlation. In this study, we investigated the relationship between bone mineral density (BMD) and serum leptin levels in 41 (28 male; 13 female, aged between 16-55 years) renal transplant recipients. The patients were grouped according to lumbar 1-4 Z-score above and below -2. Serum leptin levels were correlated with body mass index (BMI) (r=0. 431, p<0. 05). The mean serum leptin/ BMI ratio was significantly higher in patients with lumbar Z-score above -2 than in those with lumbar Z-score below -2 (0.55±0.65 vs 0.18±0.23, respectively, p<0.05). Although serum leptin/BMI ratio was correlated with lumbar1-4 Z-score ( r=0.38, p<0.05) and lumbar BMD (r=0. 32, p<0.05), no significant correlation between leptin/BMI and femoral neck Z-score was observed. In conclusion, we demonstrated that a positive correlation between serum leptin levels and lumbar Z-score, which suggests that leptin has a bone sparing effect especially in lumbar sites.